An electrical thermography audit is a systematic infrared inspection of a facility's entire electrical distribution system, from the main incoming switchboard through sub-distribution boards, motor control centres, and distribution panels, conducted to identify overheating components and connections before they cause electrical faults, fires, or unplanned downtime. A well-planned and properly executed thermography audit, repeated annually or semi-annually, is widely accepted by Singapore insurers as evidence of due-diligence fire prevention and is increasingly referenced in the SCDF Fire Code 2023 as a recommended practice for buildings with significant electrical infrastructure. This guide takes you through the complete audit lifecycle: defining scope, satisfying Singapore regulatory safety requirements, executing the inspection to a professional standard, classifying findings, and producing a report useful to maintenance planners, insurance underwriters, and compliance auditors.
Defining the Audit Scope and Safety Planning
A comprehensive electrical thermography audit for a Singapore commercial building or industrial facility typically covers the main incoming switchboard and HV/LV transformer terminals, main and sub-distribution boards, motor control centres and variable speed drive panels, power factor correction capacitor banks, UPS systems and static transfer switches, generator AMF/ATS panels and terminal boxes, external cable terminations where accessible, and busduct joint boxes. For facilities with high-voltage switchgear (11 kV or above), inspection requires specialist thermographers with HV electrical worker licensing and appropriate HV-rated PPE, a significantly more complex and hazardous undertaking than LV panel inspection. Define the scope in a written Inspection Plan before starting work, listing every panel to be inspected, the order of inspection, access requirements, and the safety controls applicable to each location.
Electrical thermography is energised electrical work, falling within the scope of Singapore's Electricity Act and the Workplace Safety and Health (Electrical Installations) Regulations. Opening live low-voltage panel doors requires the involvement of a licensed electrical worker, with a licensed HV electrical worker required for HV equipment; where arc flash risk exists, which applies to most LV switchboards above a certain prospective short circuit current, arc-rated PPE (face shield, gloves, clothing, insulating footwear) must be worn, with incident energy assessed per IEEE 1584 or a Singapore-equivalent arc flash study. Most facilities require a Permit to Work for any energised electrical work, and emergency isolation procedures and first-aid provisions must be confirmed before opening any energised panel.
Thermal Camera Setup and Inspection Technique
Camera setup directly affects the accuracy and comparability of temperature measurements. Before beginning, record the ambient air temperature in each electrical room, required for temperature rise calculations and correction factors; set the camera's emissivity to match the material being measured (bare copper ε ≈ 0.02–0.05, hard to measure accurately; oxidised copper ε ≈ 0.4–0.7; painted or insulated components ε ≈ 0.85–0.95, with a small patch of black electrical tape a practical workaround for bare copper); confirm the image is in sharp focus with the hotspot occupying a minimum area on the detector (typically 3×3 pixels or more) for a reliable spot reading; and record camera make, model, serial number, and current calibration certificate reference in the inspection log. Thermal cameras used for quantitative inspections should be calibrated at defined intervals traceable to national standards; Unitest Instruments provides SAC-SINGLAS accredited calibration for thermal cameras.
A systematic technique ensures no components are missed and findings are reproducible: photograph the panel front with label visible, open the door with appropriate PPE and a licensed electrical worker, conduct an initial full-panel scan from a safe distance before approaching closer, then systematically scan in sections, incoming terminals and busbars, each outgoing circuit breaker, then neutral and earth bars. For any hotspot, capture both thermal and visible-light images (using fusion if available), measure Tmax, identify and measure Tref on an adjacent identical component, record load current on the affected phase, and photograph the hotspot with panel label and circuit identifier visible, before closing the panel door and recording completion in the log.
Hotspot Classification and Severity Rating
Each hotspot identified must be classified by severity to guide maintenance prioritisation. The most widely used classification system uses temperature rise (ΔT) above an identical reference component:
| ΔT Above Reference | Severity | Action |
|---|---|---|
| 1–10 °C | 1. Monitor | Record and re-inspect at next scheduled survey |
| 10–20 °C | 2. Investigate | Inspect and repair at next planned outage |
| 20–40 °C | 3. Urgent | Repair within defined short window; increase monitoring |
| >40 °C | 4. Critical | Immediate repair; consider de-energising if risk allows |
Note that absolute temperature also matters. A component at 65°C in a 20°C ambient (ΔT = 45°C) is critical by ΔT classification and also approaching the standard 70°C maximum for most switchboard components. Always report both ΔT and absolute temperature in the finding record.
For findings where no comparable reference component exists (e.g. the main incoming terminals on a single-feed MSB), compare against the rated temperature for the component (from OEM data or IEC standards) rather than a reference component.
Report Structure and Content
The thermography audit report is the deliverable that maintenance planners, insurance underwriters, and compliance auditors will rely on. A professional report should contain:
- Executive summary: Total number of panels inspected, total findings by severity class, key risk items, and recommended immediate actions
- Scope and methodology: Equipment surveyed, date and time, ambient conditions, camera details and calibration certificate reference, inspection standard reference (NFPA 70B, EN 13187, or equivalent)
- Finding sheets (one per finding): Panel ID, circuit ID, component description, thermal image, visible-light image, Tmax, Tref, ΔT, ambient temperature, load current, severity classification, and recommended action with priority
- Summary findings table: All findings in a single table, sortable by severity, panel, and action status
- Inspection completion record: All panels inspected (including those with no findings) with date and inspector sign-off
- Inspector qualifications: Name, thermography certification level, electrical licence details if applicable
Post-Audit Actions and Tracking
A thermography audit report has no value unless findings are acted upon. Each finding should generate a work order in the CMMS with an assigned priority and completion deadline. Critical findings (Severity 4) should trigger immediate action regardless of whether a planned outage is scheduled. Urgent findings (Severity 3) should be completed within the next planned maintenance window.
After repairs are completed, a follow-up thermographic inspection of the repaired components confirms success. This before/after evidence is valuable for insurance purposes and demonstrates that the maintenance programme is closed-loop rather than merely identifying problems.
For the next scheduled audit, the previous report's findings summary provides the baseline for comparison. Panels that had multiple findings in the previous cycle may warrant more frequent monitoring or a closer look at load distribution and connection maintenance practices.
To discuss thermal cameras suited to electrical panel auditing or to enquire about calibration services for your existing thermal camera, contact Unitest Instruments. Related reading: thermal imaging for electrical panel inspection and thermal imaging in predictive maintenance.